Heat pipe with vaporized working fluid flow accelerator

ABSTRACT

An exemplary heat pipe includes a hollow tube, a wick structure, a working fluid, and an accelerator. The tube includes an evaporator section and a condenser section along a longitudinal direction thereof. The wick structure is adhered on inner surfaces of the tube and inner surfaces of the wick structure surround an inner space therebetween. The working fluid is contained in the wick structure. The accelerator is received in the tube and edges thereof abut against the inner surfaces of the wick structure to divide the inner space to two parts. The working fluid in the wick structure of the evaporator section absorbs heat from a heat-generating component and is vaporized to vapor, and the vapor flows through the accelerator and moves faster and faster towards the condenser section.

BACKGROUND

1. Technical Field

The disclosure generally relates to heat transfer apparatuses such as those used in electronic equipment, and more particularly to a heat pipe with high heat transfer efficiency.

2. Description of Related Art

Heat pipes are widely used in various fields for heat dissipation purposes due to their excellent heat transfer performance. One commonly used heat pipe includes a sealed tube made of thermally conductive material with a working fluid contained therein. The working fluid conveys heat from one end of the tube, typically referred to as an evaporator section, to the other end of the tube, typically referred to as a condenser section. Preferably, a wick structure is provided inside the heat pipe, lining an inner wall of the tube, and drawing the working fluid back to the evaporator section after it condenses at the condenser section.

During operation of the heat pipe in a typical application, the evaporator section of the heat pipe maintains thermal contact with a heat-generating electronic component. The working fluid at the evaporator section absorbs heat generated by the electronic component, and thereby turns to vapor. The generated vapor moves, carrying the heat with it, toward the condenser section. At the condenser section, the vapor condenses after the heat is dissipated. The condensate is then drawn back by the wick structure to the evaporator section where it is again available for evaporation. The condensate and the vapor move toward opposite directions. The vapor is prone to obstruct the movement of the condensate back to the evaporator section. Thus, a speed of the working fluid flowing back to the evaporator section decreases. Moreover, the evaporator section is then prone to becoming dry.

What is needed, therefore, is a heat pipe to overcome the above described shortcomings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lateral side, cross-sectional view of a heat pipe according to a first embodiment of the present disclosure.

FIG. 2 is a lateral side, cross-sectional view of a heat pipe according to a second embodiment of the present disclosure.

FIG. 3 is a lateral side, cross-sectional view of a heat pipe according to a third embodiment of the present disclosure.

FIG. 4 is a schematic, enlarged, isometric view of part of an accelerator of the heat pipe of FIG. 1.

DETAILED DESCRIPTION

Embodiments of the present heat pipe will now be described in detail below and with reference to the drawings.

Referring to FIG. 1, a heat pipe 10 in accordance with a first embodiment of the present disclosure is shown. The heat pipe 10 includes a sealed, flat tube 100, a wick structure 200 lining an inner surface of the tube 100, working fluid (not shown) contained in the wick structure 200, and an accelerator 300 received in the tube 100.

The tube 100 is made of metal or metal alloy with a high heat conductivity coefficient, such as copper, copper-alloy, or other suitable material. The tube 100 is elongated and has an evaporator section 110, an adiabatic section 130, and a condenser section 120 defined in that order along a longitudinal direction thereof.

The wick structure 200 is formed by weaving a plurality of metal wires such as copper or stainless steel wires, or by sintering metal powder. The wick structure 200 extends longitudinally from the evaporator section 110 to the condenser section 120. An inner space 140 is longitudinally defined between inner surfaces of the wick structure 200. The wick structure 200 draws the working fluid back to the evaporator section 110 from the condenser section 120.

Referring to FIG. 4, the accelerator 300 is located at a junction of the evaporator section 110 and the adiabatic section 130. Peripheral edges of the accelerator 300 abut against the inner surfaces of the wick structure 200 to divide the inner space 140 to two parts. The accelerator 300 includes an elongated main body 310. The main body 310 includes a first surface 311 and a second surface 312 at opposite sides thereof. The first surface 311 and the second surface 312 are parallel to each other, and respectively face the evaporator section 110 and the condenser section 120. A plurality of through holes 320 is defined in the main body 310. Each through hole 320 is tapered, and extends through the first surface 311 and the second surface 312 along a thickness direction of the main body 310. The through holes 320 resemble a plurality of nozzles in the main body 310. A diameter of each through hole 320 decreases from an inlet thereof near the evaporator section 110 to an outlet thereof facing toward the condenser section 120. A transverse cross-sectional view of each through hole 320 defines a circle. An inner surface of each through hole 320 is a smooth, frustoconical surface. The accelerator 300 is made of a metal or metal alloy with a high heat conductivity coefficient.

In the illustrated embodiment, the evaporator section 110 of the heat pipe 10 is positioned in intimate thermal contact with a heat-generating component 400 such as an electronic component. During operation of the heat-generating component 400, the working fluid in the wick structure 200 of the evaporator section 110 absorbs heat from the heat-generating component 400 and is vaporized. Thus, the vapor generates a vapor pressure which propels the vapor to flow through the through holes 320 and move towards the condenser section 120. According to the law of conservation of mass, a mass of the vapor satisfies the condition: ρ_(inlet)V_(inlet)A_(inlet)=ρ_(outlet)V_(outlet)A_(outlet), wherein ρ represents a density of the vapor, A represents a cross-sectional area of each through hole 320, and V represents a flow velocity of the vapor. The value of ρ_(inlet) is typically approximately equal to the value of ρ_(outlet). Because the diameter of the through hole 320 decreases from the inlet to the outlet, the value of A_(inlet) is larger than the value of A_(outlet). Therefore, the value of V_(inlet) is less than the value of V_(outlet). Thus, a flow velocity of the vapor increases along a flowing direction of the vapor. The vapor can accordingly rapidly transmit to the condenser section 120 for dissipation of the heat of the vapor. A heat dissipation efficiency of the heat pipe 10 can thus be improved.

On the other hand, because the diameter of each through hole 320 reduces along the flowing direction of the vapor from the evaporator section 110 to the condenser section 120, the vapor in the through hole 320 is compressed towards a center axis of the through hole 320. Thus a ratio of the vapor obstructing the condensate of the wick structure 200 in the adiabatic section 130 and the condenser section 120 is decreased, and the condensate in the adiabatic and condenser sections 130, 120 can flow back to the evaporator section 110 rapidly. According to the law of conservation of energy, the value of V_(inlet) is less than the value of V_(outlet). Therefore, the kinetic energy of the vapor at the outlet is larger than that of the vapor at the inlet of the through hole 320, and the thermal energy of the vapor at the outlet is less than that of the vapor at the inlet of the through hole 320. Thus, a condensing efficiency of the vapor can be improved.

Referring to FIG. 2, a heat pipe 20 of a second embodiment is shown. The heat pipe 20 is similar to the heat pipe 10 of the first embodiment. The heat pipe 20 includes an evaporator section 510 and a condenser section 520 defined in turn along a longitudinal direction thereof. The accelerator 300 is located at a junction of the evaporator section 510 and the condenser section 520. The first surface 311 and the second surface 312 respectively face the evaporator section 510 and the condenser section 520. A plurality of parallel fins 530 is formed on an outer periphery of the condenser section 520 of the heat pipe 20.

Referring to FIG. 3, a heat pipe 30 of a third embodiment is shown. The heat pipe 30 includes an evaporator section 610 and two condenser sections 620 located at opposite sides of the evaporator section 610, with the three sections 620, 610, 620 defined in that order along a longitudinal direction of the heat pipe 30. A plurality of parallel fins 630 is formed on an outer periphery of each condenser section 620. Two accelerators 300 are respectively located at a junction of the evaporator section 610 and one of the condenser sections 620, and at a junction of the evaporator section 610 and the other condenser section 620. The first surface 311 and the second surface 312 of each accelerator 300 respectively face the evaporator section 610 and the corresponding condenser section 620.

It is to be further understood that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

What is claimed is:
 1. A heat pipe for removing heat from a heat-generating component in thermal contact therewith, the heat pipe comprising: a hollow tube comprising an evaporator section and a condenser section defined in turn along a longitudinal direction thereof; a wick structure lining inner surfaces of the tube, inner surfaces of the wick structure defining an inner space therebetween; working fluid contained in the wick structure; and an accelerator received in the tube, edges of the accelerator abutting against the inner surfaces of the wick structure to divide the inner space into two parts; wherein the working fluid in the wick structure of the evaporator section absorbs heat from the heat-generating component and is vaporized to vapor, and the vapor flows through the accelerator and moves faster and faster through the accelerator towards the condenser section.
 2. The heat pipe of claim 1, wherein the accelerator is an elongated plate and comprises a first surface and a second surface opposite to the first surface, the first and second surfaces respectively face the evaporator section and the condenser section, a plurality of through holes is defined in the accelerator and extends through the first surface and the second surface, and the vapor flows through the through holes and moves towards the condenser section.
 3. The heat pipe of claim 1, wherein a diameter of each through hole decreases from an inlet near to the evaporator section to an outlet near to the condenser section.
 4. The heat pipe of claim 3, wherein a cross-sectional view of each through hole is circular.
 5. The heat pipe of claim 1, wherein the accelerator is made of a metal or metal alloy with a high heat conductivity coefficient.
 6. The heat pipe of claim 1, wherein the accelerator is located at a joint of the evaporator section and the condenser section.
 7. The heat pipe of claim 1, wherein a plurality of fins is formed on an outer periphery of the condenser section.
 8. The heat pipe of claim 1, wherein the tube further comprises an adiabatic section between the evaporator section and the condenser section along the longitudinal direction of the tube, and the accelerator is located at a joint of the evaporator section and the adiabatic section.
 9. The heat pipe of claim 1, wherein the tube comprises two condenser sections, the two condenser sections are located at opposite sides of the evaporator section, and two accelerators are respectively located at a joint of the evaporator section and the condenser section.
 10. The heat pipe of claim 9, wherein a plurality of fins is formed on an outer periphery of each condenser sections.
 11. The heat pipe of claim 1, wherein the tube is made of metal or metal alloy with a high heat conductivity coefficient.
 12. The heat pipe of claim 1, wherein the wick structure extends longitudinally from the evaporator section to the condenser section.
 13. A heat pipe for removing heat from a heat-generating component in thermal contact therewith, the heat pipe comprising: a hollow tube comprising an evaporator section and a condenser section defined in turn along a longitudinal direction thereof; a wick structure lining inner surfaces of the tube, inner surfaces of the wick structure defining an inner space therebetween; working fluid contained in the wick structure; and an elongated plate received in the tube, edges of the elongated plate abutting against the inner surfaces of the wick structure to divide the inner space into two parts, and a plurality of through holes defined in the elongated plate; wherein the working fluid in the wick structure of the evaporator section absorbs heat from the heat-generating component and is vaporized to vapor, and the vapor flows through the through holes and moves faster and faster in the through holes towards the condenser section.
 14. The heat pipe of claim 13, wherein a diameter of each through hole decreases from an inlet near to the evaporator section to an outlet near to the condenser section.
 15. The heat pipe of claim 13, wherein the elongated plate is made of a metal or metal alloy with a high heat conductivity coefficient.
 16. The heat pipe of claim 13, wherein an inner surface of each through hole is a smooth, annular surface.
 17. The heat pipe of claim 13, wherein a plurality of fins is formed on an outer periphery of the condenser section.
 18. The heat pipe of claim 13, wherein the tube comprises two condenser sections, the two condenser sections are located at opposite sides of the evaporator section, and two accelerators are respectively located at a joint of the evaporator section and the condenser section. 